Characterizing the Distribution of Particle Sizes in Stormwater Runoff from Ohio s Roadways

Transcription

1 Characterizing the Distribution of Particle Sizes in Stormwater Runoff from Ohio s Roadways Ryan Winston, PhD, P.E. Research Scientist Department of Food, Agricultural, and OTEC Conference 25 October 2016

2 Today s Outline: 1. Motivation for the Project 2. Literature Review on Particle Size Distribution (PSD) in Stormwater Runoff 3. Monitoring Design & Data Analysis 4. Results Next year s OTEC!

3 Impacts of Urbanization Urbanization and development increases impervious surfaces Reduces infiltration and promotes runoff Stormwater carries deposited pollutants Oil/grease Pesticides Fertilizer Metals Sediment Trash (Gross Solids) Source: mlive.com

4 Stormwater Runoff Impacts Can result in: Algal blooms fish kills habitat destruction drinking water contamination recreational area degradation Credit: SAAW International, USEPA

5 Road Runoff Nonpoint source pollution is recognized as a significant source of contamination to the world s waterways Highway specific contamination: abrasion of vehicular components deterioration of vehicle bodies burning of fuel degradation of road surfaces atmospheric deposition (Sansalone et al., 2005; Wu et al., 1998)

6 Two Most Common Pollutants? Sediment Typically analyzed as TSS Lump 0.45 µm 2mm particle sizes Trash (AKA Gross Solids) Typically >1/4 (5 mm) Diameter TMDLs in CA, MD

7 Particulate Matter in Stormwater

8 Percentage (v/v) Food, Agricultural, and In Reality High Level of Variability 5 4 in Solids at a Site 9 different storms from road site in NC Particle Diameter (µm) TSS does not tell the whole story

9 PSDs from Past Studies Food, Agricultural, and

10 Why Study Particulates? For ODOT: permit compliance Water quality treatment practices: >80% TSS removal Manufactured treatment systems L&D Vol. 2 Section Generally, remove particles >80 µm well

11 Currently Approved. ODOT Qualified Products List 21 Products Manufactured Water Quality Structure (SS-995) Advance Drainage AquaShield Contech - CDS Environment 21 - Unistorm Hydro Int. Downstream Defender All hydrodynamic separators

12 Manufactured System Treatment Processes

13 Percent Finer Food, Agricultural, and Standard PSDs for Lab Testing Sediment Particle Distributions Basic Question: Does ODOT stormwater look like this? Or like this? NJDEP Test US Silica OK110 US Silica F % TSS Removal ,000 Particle Size (µm)

14 Manufactured Device Considerations Some Cartridge Filters: 80% TARP TSS Distribution Hydrodynamic Separators: 80% ODOT Sand, 50% TARP Catch Basin Inserts: May Capture > 200 microns Cartridge (Contech) Hydro. Sep. (Contech) Basin Insert (Contech)

15 Why does Particle Size Matter? Stokes Law for Particle Settling V s = g /18m (r s - r)d s 2 V s = Settling Velocity (m/s) g = gravity (m/s 2 ) m = dynamic viscosity of water (kg/s/m) r s = density of solid (kg/m 3 ) r = density of water (kg/m 3 ) d s = diameter of solid (m)

16 Using this Information for Design Want water to remain in contact with stormwater control measure long enough trap sediment. T ahr = x sett / V s T ahr = hydraulic residence time x sett = Vertical distance particle must settle V s is settling velocity of particles

17 Theoretical Sedimentation Time 2013, Water Env Res Design Stormwater Control Measure to Required hydraulic retention time

18 Objectives of Study Characterize particle size distributions (PSDs) and TSS in road runoff across Ohio. Interested in: Different pavement type AADT/Classification Pavement Age Regional differences in rainfall Gross solids collection from road runoff Bulk volume/mass Characterization

19 Particle Size Distribution Research Image: 3P Technik UK

20 2016 Monitoring Sites I-70 I-71 3 travel lanes Very high AADT I-70: 110K VPD I-71: 133K VPD Source: ODOT traffic survey reports & maps

21 2016 Monitoring Sites SR-257 US-22 2 travel lanes Moderate to high AADT SR-257: 10K VPD US-22: 25K VPD Source: ODOT traffic survey reports & maps

22 2016 Monitoring Sites SR-48 SR-49 2 travel lanes Moderate AADT SR-48: 15K VPD SR-49: 12K VPD Source: ODOT traffic survey reports & maps

23 Sampling Design Monitor concentrated gutter flow in catch basins at 6 sites in 2016 and an additional 6 in Flow-proportional samples obtained using ISCO 6712 samplers, pressure transducers, and weirs. Rainfall measured at each site using a tipping bucket & manual rain gauge.

24 Water Quality Monitoring Isolate roadway drainage only! ODOT maintained roads Automated sampling from catch basin Measure flow depth over weir Sampler converts flow depth to flow rate Trigger samples (for instance every 50 ft 3 )

25 Water Quality Monitoring (For example SR-49) Food, Agricultural, and Pressure Transducer Sample Intake 45 v-notch weir Flow

26 Slanted Awning Forces Water Behind Weir Food, Agricultural, and Stormwater

27 Sample Analysis: PSDs Thus far, we ve sampled 79 storms for PSDs across 6 sites in 2016 PSD analyzed using Laser Diffraction Particle Counter (Beckman Coulter) Reports particle size between µm

28 Findings PSDs from roads are highly variable Appear related to local climatic factors More details at OTEC 2017 The roads we ve monitored in 2016 have been quite clean (low TSS concentrations) compared to the literature

29 Gross Solids Sampling Purpose built metal mesh netting Nominal opening 0.25 inches Drop into existing CB-3 or CB-3a Flow Diverter

30 Gross Solids Sampling Sites visited weekly All accumulated debris and trash removed and taken to lab for analysis

31 Thoughts on Gross Solids About 70-80% by volume is vegetation Remainder a mixture of cigarette butts, glass, aluminum, tires, wood, cardboard, metal Volume highly variable from ¼ gallon to as much as 20 gallons in one week Will attempt to relate to rainfall characteristics, antecedent dry period, AADT, observed mowing

32 2017 Site Selection Four Rainfall Zones: Lima (2-3 sites) Lake County (1 site) Akron/Kent (2-3 sites) Pavement Types Concrete Asphalt Roadway Classification Interstate 2 lane Rural

33 Monitoring Locations Source: ODNR

34 Expected Dataset From 12 roadway sites across OH: Approximately 150 PSDs and TSS data sampled during real rainfall events Gross solids sampled on a weekly basis Hydrographs/Hyetographs at each site Extrapolate sediment & gross solids loading

35 Questions? More Information: